The central goal of a radar system is typically to provide detection and location determination of one or more reflective possibly non-cooperative objects (RPNCO). While the physical limits of such a goal may be well understood and characterized through mathematical tools such as the radar range equation, often other considerations play a large part in the success of a given radar design in accomplishing these goals. Specifically, current radar designs sometimes suffer performance degradation when faced with tasks such as tracking and/or detecting a large number of objects at one time due to the radar's resources being overwhelmed. Other problems such as multipath interference, which can make practical detection impossible, and accurate angular position determination, which may be required for high precision tracking, can also be difficult to achieve. Each of these difficulties can be overcome to some extent by replication of radar resources, more sophisticated processing, and/or the addition of more radiative power.
Various radar techniques are currently used to determine the position and motion of a RPNCO using range and angle determination systems. Examples include the mono-static radar, multi-static radar and interferometric radar. The mono-static radar, which is the oldest of the techniques, was developed in the 1920s as a method that calculates the range to a RPNCO by measuring the time it takes for an echo of a transmitted pulse to return to a receiver complex and dividing by the speed of light. An angle determination is made by observing the direction in which the transmitter and receiver aperture are pointing. There are many refinements possible over this basic technique possible including: 1) using coherent processing of the echos to more precisely determine the range; 2) using phased array apertures, which include not one but a plurality of elements, to steer the beam electrically instead of mechanically (thereby allowing for mono-pulse angular determination, which improves angle estimation); and 3) pulse compression, which allows for long low-power pulses to replace very high-power very-short pulses resulting in a reduction of transmitter costs.
Multi-static radar typically includes a bistatic configuration where a single transmitter and a single receiver are separated by a known distance. Using the same timing techniques as those that are used in the mono-static radar case, the range and angle to the RPNCO can be determined. However, the angular accuracy is improved due to the separation distance between the transmitter and receiver.
Interferometric radars have been more recently developed to utilize a single transmitter and multiple receivers with phase comparisons of the echo received at each receiver to determine range and angle to the RPNCO relatively precisely. While each of the above described techniques is useful for either multiple object detection, high resolution tracking, or multipath mitigation under some circumstances, none of the techniques enable all of these functions to be performed in a balanced way.
In light of the issues discussed above, it is desirable to provide an improved radar system that may overcome at least some of the disadvantages described above.